电离辐射对不同放射敏感性细胞中高迁移率簇蛋白B1的诱导表达作用

目的 探讨电离辐射对已建立的宫颈癌放射抗拒细胞对比模型中高迁移率簇蛋白B1（HMGB1）和mRNA诱导表达的差异性,分析HMGB1对宫颈癌放射敏感性调控的可能性。方法人宫颈癌细胞系HeLa重复照射12次后,传代培养调整细胞状态至细胞增殖稳定,筛选得抗拒细胞系HeLaR。以2、5、10 Gy X射线分别照射亲代HeLa和HeLaR细胞,于照射后0、0.5、2、4、6、12、18、24、36、48 h收集细胞,提取蛋白质和RNA,采用Western blot和实时荧光定量PCR法分别检测样本中HMGB1蛋白和mRNA的表达情况。结果 在蛋白水平,2、5、10 Gy X射线照射后,HeLaR细胞在48 h内均表现为HMGB1表达量下降,在48 h达到未照射水平,后有增加趋势,与照射后0 h比较,2、5、10 Gy照射后6~36 h各时间点,差异具有统计学意义（t=3.574~9.754,P < 0.05）;相反,HeLa细胞在照射后6 h,其HMGB1表达逐渐增多,尤其在5和10 Gy表现明显,与照射后0 h比较,2 Gy照射后6、12、48 h（t=3.945~4.864,P < 0.05）、5 Gy照射后6、36、48 h（t=-2.875~3.295,P < 0.05）及10 Gy照射后36、48 h（t=-4.480、-4.517,P < 0.05）,差异具有统计学意义。在mRNA水平其趋势与蛋白水平基本一致。结论 不同剂量X射线照射后可诱导人宫颈癌细胞中HMGB1的表达变化,且其变化在人宫颈癌放射敏感细胞及放射抗拒细胞中不同。HMGB1可能参与人宫颈癌放射抗拒机制。     

肺癌A549放射抗拒细胞亚系的建立及抗拒机制的研究

目的 建立肺癌细胞系A549的放射抗拒模型并探讨放射抗拒的机制。方法 应用两种方案对非小细胞肺癌A549细胞系进行X射线照射:一组照射5次,每次剂量600 cGy;另一组照射15次,每次剂量200 cGy。照射完成后对存活细胞单克隆化分别命名为A549-S1和A549-S2,采用克隆形成实验测定两种细胞亚系及亲本A549细胞的放射敏感性,流式细胞术检测细胞周期特征,RT-PCR和Western blot分别测定3种细胞Notch1的表达。结果 与亲本A549细胞相比,A549-S1细胞显示出明显放射抗性,D₀、D_q及N值增大,细胞存活曲线肩区增宽,在SF₂水平上,放射抗性是A549的1.38倍,细胞的S期比例较A549细胞明显增高, G₀/G₁期比例下降(P<0.05),Notch1的表达较A549细胞明显增强。而A549-S2的放射敏感性与亲本细胞相比稍增强,D₀、D_q及N值均减小,细胞存活曲线肩区变窄,在SF₂水平上,放射抗性是A549细胞的0.84倍,细胞S期、G₀/G₁期比例较A549细胞减少,而G₂/M期比例明显增加(P<0.05),Notch1表达与亲本A549细胞相比无明显变化。结论 A549细胞亚系放射抗拒的形成与不同照射方案有一定关系,得出的放射抗拒细胞亚系显示出与亲本不同的细胞周期特征,而细胞特征的变化可能与Notch1的表达增强有关。     

鼻咽癌细胞放射敏感性的比较蛋白质组学研究

目的 探讨与鼻咽癌细胞放射敏感性相关的并可能预测鼻咽癌细胞放射敏感性的蛋白质。方法 以人鼻咽癌细胞株CNE-2诱导建立放射抗拒的鼻咽癌细胞株CNE-2(R743),通过克隆形成实验及流式细胞术检测以比较CNE-2和CNE-2(R743)细胞的放射敏感性及细胞周期的特征。提取细胞总蛋白质,进行双向凝胶电泳,Image Master 7.0图像分析软件分析图谱以识别差异蛋白质点,MALDI-TOF/TOF肽质量指纹图谱分析,蛋白质质谱数据库搜索鉴定差异蛋白。应用RT-PCR和Western blot验证2种细胞中相关差异蛋白的表达。 结果 得到7个差异表达较显著的蛋白质,与CNE-2相比较,CNE-2(R743)细胞中6个上调,1个下调。Western blot及 RT-PCR证实膜联蛋白A2、原肌球蛋白及糖调节蛋白78在CNE-2(R743)的表达均上调(t=24.22、24.20和29.19,P<0.05),与蛋白质组学结果一致。结论 不同放射敏感性鼻咽癌细胞存在差异表达的蛋白质,其中膜联蛋白A2、原肌球蛋白及糖调节蛋白78有可能成为预测鼻咽癌细胞放射敏感性的候选生物标志物。     

γ射线增强喉癌细胞hTERTp启动子活性研究

目的 探讨γ射线对喉癌细胞中端粒酶逆转录酶基因启动子(hTERTp)活性的影响,以及通过射线增强hTERTp下游基因表达的可行性。方法 将含hTERTp的质粒转染细胞,采用报告基因评价启动子活性,通过RT-PCR和酶活性检测观察射线作用下hTERTp调控辣根过氧化物酶(HRP)的表达,克隆形成实验评价射线对phTERTp-HRP/IAA杀伤和放射增敏作用的影响。结果 在Hep-2细胞中,6 Gyγ射线照射后hTERTp活性是0 Gy照射后的2.96倍,在Hep-2R细胞中是1.60倍。质粒phTERTp-HRP转染Hep-2和Hep-2R细胞后,6 Gy照射组的HRP mRNA分别增高2.1和1.1倍,酶活性分别增高2.54和1.23倍。6 Gy联合吲哚乙酸(IAA)组Hep-2细胞的存活分数为1.3%,Hep-2R细胞的存活分数为3.5%,比对照组明显降低(F=234.280和F=357.148,P值均<0.01)。6Gy联合IAA组与IAA组相比,放射增敏比SER_<sub>SF2分别为1.52(Hep-2)和1.68(Hep-2R),存活曲线的参数α分别为0.416、0.099(Hep-2)和0.356、0.090(Hep-2R)。结论 γ射线可以增强不同放射敏感性喉癌细胞hTERTp活性,增强下游基因表达。射线联合phTERTp-HRP/IAA对喉癌细胞具有更加明显的杀伤和放射增敏作用。     

RNA干扰抑制c-jun基因表达对放射抗拒人鼻咽癌细胞系CNE-2R放射敏感性的影响

目的 利用RNA干扰技术抑制放射抗拒人鼻咽癌细胞系CNE-2R中高表达的c-jun基因,研究其对CNE-2R细胞放射敏感性的影响及其潜在机制.方法 设计合成3组特异性针对c-jun基因的siRNA,构建慢病毒vshRNA载体,感染CNE-2R细胞,采用RT-PCR和Western blot方法检测各组对目的基因的抑制效果;并通过克隆形成实验测定其放射敏感性,CCK-8实验检测细胞的存活能力,流式细胞术检测细胞凋亡率.结果 重组慢病毒c-jun-RNAi-LV2能明显下调CNE-2R细胞中c-jun的mRNA和蛋白水平的表达(F=217.20、42.07, P<0.05).6 MV X射线联合c-jun-RNAi-LV2组在0、2、4、6和8 Gy照射后细胞的吸光度值均显著低于未转染组和阴性对照组(F=42.70~200.67, P<0.05).克隆形成实验显示,c-jun-RNAi-LV2组与未转染组及阴性对照组相比,SF₂、D₀和D_q值均减小,放射增敏比(SER_D0)为1.41.细胞凋亡实验结果显示,未经照射的c-jun-RNAi-LV2组与联合2 Gy照射的凋亡率分别为(20.93±1.99)%和(38.17±0.83)%,均高于未转染组和阴性对照组的凋亡率[0 Gy:(10.97±0.70)%和(20.43±0.25)%;2 Gy:(10.80±1.25)%和(19.53±1.50)%;F=50.54、330.14, P<0.05].结论 RNA干扰技术可有效抑制放射抗拒人鼻咽癌细胞系CNE-2R中高表达的c-jun基因,使细胞放射敏感性增高,其作用可能与c-jun基因的下调使细胞增殖能力减弱,细胞凋亡增多有关.     

低温等离子体联合辐射对三种癌细胞系放射增敏效应的研究

目的 探讨低温等离子体对人肝癌细胞系HepG2、非小细胞肺癌细胞系A549及人宫颈癌细胞系HeLa的放射增敏作用及其机制。方法 应用克隆形成实验观察低温等离子体对3种细胞的放射增敏作用;流式细胞仪分析3种细胞周期分布、凋亡率及活性氧含量;Western blot法检测单纯照射(R组)、单纯等离子体作用(P组)及其联合辐射(P+R组)对3种细胞中Bcl-2、Caspase-3蛋白表达的影响。结果 低温等离子体对HepG2、A549及HeLa细胞均有放射增敏作用,放射增敏比(SER_D0)分别为1.28、1.32、1.29。HepG2、A549及HeLa细胞P+R组G₂/M期比例、凋亡率及活性氧含量与R组比较均明显增高(t_G2/M期=9.52、8.24、9.53,P<0.05;t_凋亡率=10.67、38.56、6.74,P<0.05;t_{活性氧含量}=9.41、15.42、13.53,P<0.05)。HepG2和A549细胞P+R组G₂/M期比例、凋亡率及活性氧含量与P组比较均明显升高(t_G2/M期=8.75、20.37,P<0.05;t_凋亡率=8.43、9.99,P<0.05;t_{活性氧含量}=4.82、5.27,P<0.05)。3种癌细胞中P+R组Bcl-2蛋白表达较R组降低,而Caspase-3蛋白表达升高。结论 低温等离子体可提高HepG2、A549及HeLa细胞系的放射敏感性,其对HepG2及A549细胞系的放射增敏机制可能与抑制亚致死损伤修复,使细胞周期阻滞在G₂/M期,以及提高细胞内ROS水平诱导细胞凋亡有关。     

沉默STAT1基因增强放射抗拒鼻咽癌CNE-2R细胞放射敏感性

目的 研究基因STAT1沉默对人放射抗拒鼻咽癌细胞放射敏感性的影响.方法 慢病毒介导的STAT1基因转染放射抗拒鼻咽癌细胞CNE-2R,荧光定量RT-PCR技术检测沉默效果.MTT法检测转染前后细胞增殖活性,流式细胞技术检测细胞周期及凋亡,克隆形成实验检测转染前后细胞放射敏感性变化.结果 慢病毒转染后放射抗拒鼻咽癌细胞STAT1表达降低(F=429.87,P<0.05)、细胞生长抑制(F3=.88~4.63,P<0.05)、凋亡率增加(F=38.13,P<0.05)、放射敏感性增加(F=252.80,P<0.05)、细胞周期中G₀/G₁、S和G₂/M期未见明显差异(P>0.05).结论 沉默STAT1基因能增加放射抗拒鼻咽癌细胞 CNE-2R的放射敏感性.     

二氢青蒿素对人宫颈癌HeLa细胞放射增敏作用的研究

目的 探讨二氢青蒿素对人宫颈癌HeLa细胞的放射增敏作用。方法 用MTT法检测其对HeLa细胞生长的抑制效应;克隆形成法检测放射敏感性;应用流式细胞仪检测细胞周期及细胞凋亡的变化。结果 二氢青蒿素对HeLa细胞有明显的抑制作用,其效应呈时间和剂量依赖性。20 μmol/L二氢青蒿素对HeLa细胞的放射增敏比(SER)为1.47。二氢青蒿素能够去除X线导致的HeLa细胞G₂期阻滞,与单纯6 Gy照射组相比,药物+照射组G₂期阻滞由73.58%降至48.31%。二氢青蒿素能增强X线诱导的细胞凋亡,与单纯2、4、6 Gy照射组相比,药物+照射组凋亡率分别由29.46%、48.04%、70.21%升至45.79%、66.36%、79.58%。结论 二氢青蒿素对人宫颈癌HeLa细胞具有放射增敏作用,机制可能与二氢青蒿素去除照射引起的G₂期阻滞有关。     

青蒿素对人鼻咽癌CNE细胞的放射增敏作用及机制的研究

目的 探讨青蒿素对人鼻咽癌CNE细胞的放射增敏作用。方法 应用甲基偶氮唑盐(MTT)比色法检测青蒿素对鼻咽癌CNE细胞的抑制效应;克隆形成实验观察青蒿素对CNE细胞的放射敏感性的影响;流式细胞术测定照射后CNE细胞周期的再分布。结果 青蒿素对CNE细胞的抑制率呈药物剂量依赖性增加。青蒿素能明显增加γ射线对CNE细胞的克隆形成抑制作用,1 μmol/L青蒿素对CNE细胞的放射增敏比(SER)为1.26。青蒿素能够去除γ射线照射后CNE细胞的G₂/M期阻滞,与单纯6 Gy照射组相比,青蒿素+照射组G₂/M期阻滞减少。结论 青蒿素通过减弱辐射诱导的G₂/M期阻滞,从而增加γ射线对CNE细胞的杀伤作用。     

过表达miR-29c靶向抑制AKT2增强肝癌HepG2细胞放射敏感性的实验研究

目的 探讨miR-29c靶向AKT2对肝癌细胞HepG2放射敏感性的影响。方法 RT-PCR检测人正常肝THLE-3细胞和肝癌HepG2细胞中miR-29c表达。给予不同剂量（0、2、4、6和8 Gy）的X射线照射后,RT-PCR检测HepG2细胞中miR-29c表达变化。经生物信息学预测并采用双荧光素酶报告基因实验和Western blot检测miR-29c与AKT2的靶向关系。采用脂质体2000将miR-29c mimic/AKT2基因重组质粒和miR-29c inhibitor/慢病毒载体AKT2 shRNA转染至HepG2细胞中,并给予不同剂量X射线照射后,克隆形成实验和MTT实验检测miR-29/AKT2对HepG2细胞存活率和细胞活力的影响。结果 与THLE-3细胞相比,HepG2细胞中miR-29c明显降低,差异有统计学意义（t=17.816,P<0.05）;HepG2经2、4、6和8 Gy X射线照射后,细胞存活率较THLE-3细胞显著降低（t=4.541、6.823、7.218、9.363,P<0.05）,HepG2细胞中miR-29c表达显著下降（t=5.599、9.262、10.470、10.873,P<0.05）。miR-29c过表达可降低HepG2细胞存活率和细胞活力（t_存活率=4.307、7.668、7.668、6.894,P<0.05;t_细胞活力=3.443、8.116、13.434,P<0.05）;反之,抑制miR-29c表达则升高HepG2细胞存活率和细胞活力（t=4.003、6.713、7.141,P<0.05;t_细胞活力=4.282、5.113,P<0.05）。双荧光素酶报告基因实验表明,AKT2是miR-29c的靶基因,Western blot检测结果显示,miR-29c可负向调控AKT2蛋白表达。沉默AKT2后,HepG2细胞的存活分数及细胞存活率趋势与miR-29c过表达相一致;反之,AKT2过表达则与抑制miR-29c表达相一致。结论 miR-29c可通过靶向AKT2增加肝癌细胞HepG2放射敏感性。     

Pentoxifylline Enhances Tumor Oxygenation and Radiosensitivity in Rat Rhabdomyosarcomas during Continuous Hyperfractionated Irradiation

PURPOSE: To examine the influence of the hemorrheologic agent pentoxifylline (PTX) on tumor oxygenation and radiosensitivity. MATERIAL AND METHODS: Tumor oxygenation in rat rhabdomyosarcomas R1H after PTX administration (50 mg/kg body weight) was measured using interstitial pO(2) probes (Licox CMP system and Eppendorf pO(2)-Histograph). Tumors were irradiated with (60)Co gamma-irradiation using single doses (15 and 30 Gy), conventional fractionation (60 Gy/30 fractions/6 weeks), and continuous hyperfractionation (54 Gy/36 fractions/18 days) in combination with PTX or an equivalent volume of physiological saline. Radiation effects were determined by tumor growth delay (2V(o)), and by partial and complete tumor remission. RESULTS: PTX increased tumor oxygenation for up to 45 min after administration of the drug. Single doses of 15 and 30 Gy of irradiation, when combined with PTX, produced little radiosensitization of the R1H tumors as indicated by dose-modifying factors (DMFs) of 1.11 and 1.04, respectively. In conventional fractionated irradiation with PTX, a DMF of 1.10 was obtained only. However, in continuous hyperfractionated irradiation with 18 x 50 mg/kg of PTX, the DMF with respect to tumor growth delay was found to be 1.37. Local tumor control was not influenced by PTX. In vitro studies identified R1H cells as p53 wildtype and showed a G1 arrest in response to irradiation. When 2 mM PTX was given prior to irradiation, it did not improve radiosensitivity of R1H cells as measured by clonogenic survival assays. CONCLUSION: PTX effectively enhances tumor oxygenation and radiosensitivity of R1H rhabdomyosarcomas, especially during continuous hyperfractionated irradiation. Given to rats as an adjuvant to fractionated irradiation, PTX does not enhance acute or late skin reactions or tumor metastasis. No radiosensitization was observed in vitro, when oxygen was not limiting. The observed radiosensitization by PTX is caused mainly by improved tumor oxygenation.     

放射抗拒性食管癌细胞系的建立及基因表达差异分析

目的观察食管癌细胞经射线反复照射后放射敏感性的变化，应用基因芯片技术分析放射抗拒性食管癌细胞基因表达变化。方法食管鳞状细胞癌细胞株TE13经反复γ射线照射（累积剂量120Cy），逐步筛选出具有放射抗拒性的细胞TE13R120。相差显微镜下观察TE13及TE13R120的形态学差异；应用细胞克隆形成实验，验证TE13及TE13R120两种细胞的不同放射敏感性，用流式细胞术检测它们的细胞周期分布特征；基因芯片分析两种细胞基因表达差异。结果TE13R120的细胞群体倍增时间为39．93h，长于亲代TE13（33．94h）。TE13及TE13R120的放射敏感性明显不同（仇值分别为1．63和2．85Gy，SF2值分别为0．55和0．64，Dq值分别为1．38和1．15Gy，n值分别为2．33和1．49）。两种细胞经4Gy放射线照射后，出现不同的细胞周期分布改变，12～48h TE13R120细胞周期变化不明显，而其亲代细胞TE13发生明显G1期阻滞。应用DNA芯片对2159个基因进行了筛选，TE13R120与TE13相比，上调基因96个，下调基因80个。结论新的食管癌细胞系TE13R120比其亲本对射线更加抗拒，并且在基因水平上发生明显变化。4Gy照射后12～48hTE13R120细胞周期变化不明显，而其亲代细胞TE13发生明显G1期阻滞。     

Effect of growth rate of monolayer cells on survival after fractionated irradiation]

This study was performed to determine the effect of the growth rate of monolayer cells on survival following fractionated irradiation. HeLa and RMUG cells that had different radiosensitivities and growth rates (Do value: 2.3 vs 1.5 Gy, doubling time: 17 vs 46 hours) were irradiated with 2 Gy every day. The fractions surviving after fractionated irradiation were compared with those given single doses. The dose modifying factor for fractionated irradiation was larger in RMUG than HeLa: 1.7 and 1.2, respectively. Two clones from ADGU cells that had the same radiosensitivity but different growth rates were also given fractionated irradiation, but there was no difference in surviving fractions. When recovery following two split doses was determined in each type of cell, the results of the fractions surviving after fractionated irradiation were correlated only with recovery between split doses. These suggest that the growth rates of monolayer cells may not modify the fractions surviving after fractionated irradiation, and the monolayer cell system is not suitable for determining the effect of growth rates on survival following fractionated irradiation.     

线粒体DNA4977bp缺失和彗星分析评价肿瘤细胞的辐射敏感性

目的 探讨mtDNA4977bp缺失和彗星分析用于肿瘤细胞辐射敏感性检测的可行性。方法 选取3种不同肿瘤细胞株:肝癌细胞(HepG₂)、食管癌细胞(EC-9706)和乳腺癌细胞(MCF-7)。采用MTT法检测肿瘤细胞经γ射线照射后的存活分数(SF);巢式PCR法测肿瘤细胞的mtDNA4977bp缺失率;单细胞凝胶电泳(SCGE)检测肿瘤细胞的DNA断裂水平。结果 用MTT法发现HepG₂ 和EC-9706细胞的辐射敏感性高于MCF-7细胞。8 Gy照射后HepG₂和EC-9706 mtDNA4977bp缺失率明显高于MCF-7细胞(P<0.05),证实HepG₂和EC-9706细胞的辐射敏感性高于MCF-7细胞。多种方法分析结果说明3种肿瘤细胞在8Gy照后表现出的辐射敏感性差异有统计学意义。结论 多种生物学指标的综合应用,可能更加客观准确地评价肿瘤细胞的辐射敏感性。     

Upregulating DAB2IP expression via EGR-1 inhibition,a new approach for overcoming fractionated-irradiation-induced cross-tolerance to ionizing radiation and mitomycin C in tumor cells

Purpose: To evaluate the effect of fractionated irradiation (FI) on tumor cells’ sensitivity to ionizing radiation (IR) and antineoplastic drugs, and examine the potential of early growth response-1 (EGR-1) inhibition to sensitize tumor cells to IR.

Materials and methods: PC3 and HepG2 cells were subjected 10 times to γ-rays at 2?Gy. The surviving cells were named PC3/R and HepG2/R, respectively. The cells’ sensitivity to irradiation and chemotherapeutic drugs, including cisplatin (PT), doxorubicin (DOX), mitomycin C (MMC) and 5-fluorouracil (5-FU), were identified by colony formation assay and MMT method, respectively. Quantitative real-time polymerase chain reaction (RT-qPCR) analysis was utilized to compare the difference of gene expression between radioresistant cells and parental cells. The small interfering RNA system was implemented to inhibit endogenous EGR-1 expression in radiation-resistant cells. Western blot was employed to identify the possible mechanism by which EGR-1 regulates cells’ radiosensitivity.

Results: FI induced cross-resistant to IR and MMC in tumor cells. Along with the reduction of ovarian cancer-2/disabled homolog 2 (DOC-2/DAB2) interactive protein (DAB2IP) expression, EGR-1 gene was upregulated in FI-treated cells. On the other hand, downregulation of EGR-1 gene expression sensitized radioresistant cells to IR accompanied by DAB2IP overexpression and STAT3 inactivation. In addition, NF-κB inhibitor, BAY11-7082 enhanced resistant cells’ radiosensitivity and chemosensitivity.

Conclusions: Conventionally FI has a higher risk of forming acquired radioresistance (ARR) in vitro. EGR-1 gene-targeted drug design could be an effective strategy to overcome DAB2IP-dysregulation-induced ARR in tumor patients.     

脑胶质瘤SHG-44细胞株照射后子代辐射敏感性

目的 探讨脑胶质瘤SHG-44细胞株照射子代生长特性及辐射敏感性变化。方法 培养人脑胶质瘤SHG-44细胞株照射后的存活子代细胞,测定其群体倍增时间,并进行集落形成实验和流式细胞仪检测,分析其辐射敏感性和细胞周期变化。结果 SHG-44细胞群体倍增时间为(22.78±2.61) h,SHG-44细胞经6 MV X射线10 Gy照射后存活子代SHG-44.10细胞群体倍增时间为(30.46±2.73) h (F=7.878,P<0.05)。SHG-44细胞和SHG-44.10细胞再次2 Gy照射后的存活分数分别为70.8%、80.6%。与SHG-44细胞相比,SHG-44-10细胞在G₂/M期比例减少,S期比例增多。结论 SHG-44细胞照射后存活子代细胞增殖延缓,辐射敏感性下降。     

野生型p53基因转染卵巢癌SKOV-3细胞对放疗敏感性的影响

目的 探讨γ射线照射抑制平滑肌细胞（SMC）增殖的信号传递途径。方法 培养的动脉平滑肌细胞分别接受吸收剂量为3.5、7．0、14Gy^60Coγ射线照射后，以^3H-TdR掺入法测定平滑肌细胞增殖程度，放射活性法测定蛋白激酶C（PKC）及丝裂素活化蛋白激酶（MAPK）活性。结果 7．0、14Gy^60Coγ射线能明显抑制平滑肌细胞增殖，同时有MAPK、PKC活性明显降低。结论 7．0、14Gy^60Coγ射线抑制血管平滑肌细胞增殖可能是通过降低MAPK、PKC活性途径实现的。     

Cytokinetic and cytotoxic responses of HeLa cells to the combination of hyperthermia and radiation

Colony formation and cell cycle changes of HeLa cells were studied after the combination of hyperthermia and 60Co irradiation. Cells were heated by immersion in a water bath. The cell cycle progression was monitored using flow cytometry. The dose survival curve of asynchronous growing cells, with immediate postirradiation thermal treatment at 43 degrees C for 60 min, showed significant enhancement of radiosensitivity. When the sequence of heat and irradiation was varied, the greatest decrease in cell survival was obtained when irradiation was given immediately before or after thermal treatment. Flow cytometry analysis showed that irradiation of exponentially growing cells with 5 Gy induced a G2 block, and that heat treatment immediately after 5 Gy exposure caused a progression delay of the cells from G2 + M to G1 phase. Furthermore, the cellular DNA histogram at 48 hours after 5 Gy exposure, immediately before heating, had more cells in G2 + M phase as compared with cells exposed to 5 Gy alone or thermal treatment at 5 hours before or after 5 Gy exposure. These results suggest that hyperthermia immediately after irradiation inhibits some of the cells accumulated in G2 + M phase from traversing into G1 phase. This inhibition may be related to the synergistic cell-killing by hyperthermia and radiation.     

不同分割照射对胰腺生物学效应的影响

目的 探讨不同分割模式X射线照射后大鼠胰腺的损伤程度。方法 将健康成年Wistar大鼠80只,随机分为常规分割组,12 Gy分6次照射,每天1次;单次大剂量组,一次性照射12 Gy;中等低分割组,12 Gy分2次照射,中间间隔4 d;对照组,给予假照;每组20只。于照射前及照射后4、7、14、21和42 d称重、测空腹血糖、淀粉酶,观察胰腺组织学改变。结果 各实验组血糖照射后4 d时降至最低,最低时达(3.1±0.1)mmol/L,(LSD-t=20.06~28.74,P<0.001),单次大剂量组较常规分割组、中等低分割组降低更明显(LSD-t=8.72~9.71,P<0.001),常规分割组、中等低分割组差异无统计学意义,14 d及以后接近正常;血淀粉酶照射后4和7 d时升高,最高时可达(84.5±6.4 )U/L(Dunnett's-t=23.10~46.10,P<0.001),7 d时单次大剂量组较常规分割组、中等低分割组升高更明显(Dunnett's-t=7.11,P<0.05),常规分割组与中等低分割组比较差异无统计学意义,14 d及以后恢复正常。光镜下,单次大剂量组4 d时个别腺泡变性坏死,14 d时腺管周围间质纤维增生,21 d时胰岛细胞间纤维增生,42 d时腺细胞增生。常规分割组、中等低分割组出现同样变化,仅程度较轻,出现较晚。结论 当分次剂量及间隔时间合适时,中等低分割照射损伤程度未超过常规照射,这对临床非常规放疗的开展有一定的参考价值。